Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

Diss. Linköping : Univ., 2000.

This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

Change of DNA methylation is a hallmark of cancer. It is frequently associated with cancer progression. Testicular germ cell tumor (TGCT) is the most common malignant tumor in young males. Currently, only a limited number of genes are known to be epigenetically changed in TGCT. Genome-wide analysis of differential methylation in a previously established testicular cell line is documented here. A total of 35,208 differentially methylated regions (DMR) were identified. However, only a small number of DMRs mapped to gene promoters. Genome-wide analysis of gene expression revealed a group of differentially expressed genes that were regulated by DNA methylation. Several candidate genes ( APOLD1, PCDH10 and RGAG1) were found to be dysregulated in TGCT patients. Surprisingly, APOLD1 was mapped to the TGCT susceptibility locus at 12p13.1, suggesting that it may be important in TGCT pathogenesis. / The majority of DMRs are located in introns or intergenic regions, but their functions are not well understood. Some of these DMRs were found to regulate non-coding RNAs (ncRNAs). In this study, differential methylation of 3 small nucleolar RNAs (snoRNA) and 3 microRNAs (miRNA) were identified. One of the miRNAs, miR-199a, is embedded in a conserved region in intron-14 of dynamin 3 at 1q24.3. Hypermethylation of miR-199a correlated with testicular cancer progression, and silencing of miR-199a. Re-expression of miR-199a in testicular cancer cells suppressed cell growth, cancer migration, invasion, and metastasis. miR-199a-5p, one of two mature miRNA species derived from miR-199a, is associated with cancer progression. An embryonal carcinoma antigen, podocalyxin-like protein 1 (PODXL), was identified to be a target of miR-199a-sp. PODXL is an anti-adhesive protein overexpressed in aggressive testicular cancer. Knockdown of PODXL suppressed cancer invasion. The inverse relationship between PODXL and miR-199a-5p expression suggests that PODXL is one of the downstream effectors mediating cancer invasion and metastasis. This study links DNA methylation, miR-199a dysregulation, and PODXL expression as a mechanism to explain testicular cancer progression. / Cheung, Hoi Hung. / Adviser: Woi-Yee Chan. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 165-192). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

It was previously demonstrated that miR-199a was down-regulated in testicular germ cell tumor (TGCT) partly caused by hypermethylation of its promoter. More detailed analyses showed that miR-199a-5p, one of its two derivatives, suppressed TGCT invasiveness and proliferation via directing targeting PODXL and MAFB. The biological role of the other derivative, miR-199a-3p in TGCT, remains largely uncharacterized. In this project we identified DNMT3A, the de novo methyltransferase, as a direct target of miR-199a-3p using a 3’-UTR reporter assay. In NT2 (NTera 2) and HT (Hs 1.Tes) cells, miR-199a-3p regulated the expression of endogenous DNMT3A (both DNMT3A1 and DNMT3A2 isoforms), especially DNMT3A2 isoform. In clinical samples, the expression of DNMT3A2 and miR-199a-3p were reciprocally regulated. However, DNMT3A did not regulate miR-199a expression. Further characterization of miR-199a-3p revealed that it negatively regulated DNA methylation partly through targeting DNMT3A. MiR-199a-3p could restore the expression of APC and MGMT via de-methylation in their promoters. Our studies demonstrated the dysregulation of miR-199a-3p in TGCT may provide novel mechanistic insights into TGCT carcinogenesis and suggested a potential therapeutic use of synthetic miR-199a-3p oligonucleotides as effective demethylation agent in the treatment of TGCT. However, since DNMT3A expression did not regulate miR-199a expression, the mechanism of promoter DNA hypermethylation of miR-199a in TGCT needs further investigation. / MiR-199a is encoded by two loci in the human genome, namely, miR-199a-1 on chromosome 19 and miR-199a-2 on chromosome 1. Another microRNA, miR-214, also locates on chromosome 1. Previous study revealed that it is co-transcribed with miR-199a-2, which is directed by miR-199a-2 promoter. However, the biological significance of the co-expression of miR-199a and miR-214 remains largely unknown. In this project, it was determined that miR-199a and miR-214 were concordantly expressed in TGCT. Silencing of DNMT1 increased the expression of miR-199a and miR-214, accompanied by de-methylation in the promoters of miR-199a-1/2. Overexpression of TP53 down-regulated the expression of DNMT1 and increased the expression of mature miR-199-3p/5p and miR-214. In addition, silencing of PSMD10 up-regulated the expression of TP53, while miR-214 over-expression resulted in PSMD10 down-regulation and TP53 up-regulation. Collectively, our findings highlighted a miR-199a/miR-214/PSMD10/TP53/DNMT1 self-regulatory network, which caused the down-regulation of miR-199a, miR-214 and TP53, as well as the up-regulation of DNMT1 and PSMD10 in TGCT. These observations partly explain the mechanism of promoter DNA hypermethylation in miR-199a in TGCT. They also suggest a potential therapeutic approach by targeting the miR-199a/miR-214/PSMD10/TP53/DNMT1 regulatory network in the treatment of TGCT. / 先前的研究證實miR-199a在睾丸生殖細胞腫瘤 (簡稱睾丸癌) 中是低表達的，部分歸因於其啟動子區域過度甲基化。對其功能研究發現miR-199a能抑制睾丸癌細胞的生長，侵襲和轉移，且miR-199a的抑癌屬性應歸功於它的兩個衍生物之一miR-199a-5p。然而，miR-199a的另一個衍生物miR-199a-3p在睾丸癌中的生物學功能仍然在很大程度上是未知的。此研究中，DNMT3A被鑒定為miR-199a-3p的直接靶定目標。在NT2和HT細胞中，miR-199a-3p能調控內源性DNMT3A(DNMT3A1和DNMT3A2)的表達水準，尤其是DNMT3A2。在臨床樣本中，DNMT3A2的表達水準與miR-199a-3p的表達水準呈負相關。但DNMT3A並不能調控miR-199a的表達水準。進一步研究顯示過表達miR-199a-3p能減少APC和MGMT啟動子區域甲基化而恢復其表達水準。研究證實異常表達的miR-199-3p可能在睾丸癌的癌變過程中發揮作用，並提出一個潛在的治療方案，即使用miR-199a -3p作為有效的去甲基化藥劑治療睾丸癌。然而睾丸癌中導致miR-199a啟動子區域過度甲基化的機制有待進一步研究。 / 在人類基因組中，miR-199a-1(位於19號染色體)和miR-199a-2(位於1號染色體)都編碼miR-199a。同時miR -214也位於1號染色體，研究表明miR-214與miR-199a-2由miR-199a-2啟動子介導共同轉錄，但miR-199a和miR- 214共同表達的生物學意義仍未知。此研究中，miR-199a和miR-214在睾丸癌中的表達呈現一致性。沉默DNMT1後miR-199a和miR-214的表達水準顯著提高，並伴隨著miR-199a-1/2啟動子區域的DNA去甲基化。在NT2細胞中。過表達TP53能下調DNMT1的表達水準，同時上調miR-199-3p/5p和miR- 214的表達水準。此外，過表達miR -214能導致PSMD10表達水準的下調以及TP53表達水準的上調。綜上所述，我們提出一個miR-199a/miR-214/PSMD10/TP53/DNMT1自我調控網路，此調控通路能引起睾丸癌中miR-199a，miR-214和TP53表達水準的下調，以及DNMT1和PSMD10表達水準的上調，且部分解釋睾丸癌中miR-199a啟動子區域過度甲基化的機制，同時該調控網路可作為治療睾丸癌的一個潛在靶點。 / Chen, Bifeng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 103-127). / Abstracts also in Chinese. / Title from PDF title page (viewed on 20, December, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 5 uppsatser.

Les tumeurs germinales du testicule (TGCT) sont la forme de cancer la plus fréquente chez les hommes jeunes (15-39 ans). Un rôle de l'environnement au moment de la période prénatale est suspecté, mais aucune étiologie claire ne semble émerger. Cette thèse avait pour but de développer une nouvelle approche épidémiologique pour étudier l'impact des expositions prénatales aux pesticides sur le risque de TGCT. Par une revue de la littérature, nous avons tout d'abord montré le manque d'études sur les expositions prénatales et le besoin de méthodes fiables pour évaluer l'exposition environnementale aux pesticides. Ensuite, par une campagne de mesures domestiques dans 239 foyers, nous avons identifié les déterminants environnementaux de l'exposition aux pesticides agricoles. La surface des cultures dans un rayon de 500m (vergers) ou 1000m (céréales/vignes), le vent et les barrières végétales ont été identifiés comme déterminants de l'exposition. La bonne efficacité de notre lingette en cellulose a été testée en laboratoire. Nos résultats montrent également l'importance des utilisations domestiques de pesticides sur la contamination des foyers. Enfin, à travers une étude cas témoins pilote, nous avons confirmé notre capacité à recruter des sujets et leurs mères, ainsi que les informations requises pour évaluer les expositions jusque dans les années 70. Pour conclure, nos résultats ont permis le développement d'une étude cas-témoins nationale (projet TESTIS) pour étudier l'impact des expositions prénatales aux pesticides sur le risque de TGCT. Ce projet a été financé et est en cours de réalisation. Cette thèse sert également de base à plusieurs autres projets multidisciplinaires / Testicular germ cell tumors (TGCT) are the most common cancers in men aged 15–39 years. Environmental exposures occurring in the prenatal period are suspected to play a role, but no clear associations with TGCT risk are known. This thesis aimed to develop an epidemiological approach to study the impact of prenatal exposures to pesticides on the TGCT risk. First, through a systematic literature review, we identified a gap in knowledge regarding prenatal exposures, as well as the need for more reliable assessment of environmental pesticide exposures. Second, through a survey of indoor dust sampling in 239 households, we identified the environmental determinants of agricultural pesticide exposure to develop a metric to assess environmental pesticide exposures using a geographical information system. Crop acreage within 500m (orchards) or 1000m (cereals/vineyards), wind, and vegetative barriers were identified as determinants of the indoor contamination. The overall good efficiency of our cellulose wipe was assessed through laboratory experiments. Our results also suggested domestic pesticide use as a major source of households’ pesticide exposure. Third, through a case-control pilot study we tested different approach to recruit young men and their mothers, and we confirmed our ability to collect information about their exposures, and to map precisely their addresses until the 1970’s. Our findings lead to the development of a national case-control study (TESTIS project) aiming to assess the impact of prenatal pesticides exposures on the TGCT risk. This project has been funded and is currently on-going. Our research also serves as basis for further multidisciplinary projects